1. Field of the Invention
The present invention relates to an X-ray imaging apparatus that obtains an X-ray image from X-rays transmitted through a subject, and more particularly, to a movable X-ray imaging apparatus for use in image taking performed, for example, at home or at the time of disaster.
2. Description of the Related Art
There are known movable X-ray imaging apparatuses that are moved to the bedside in a patient's room to take an X-ray image of a subject in a state in which an X-ray device is mounted on a carriage. In these X-ray imaging apparatuses, a storage box storing an X-ray film cassette and the like is often provided integrally with an X-ray control unit.
Japanese Patent Laid-Open No. 2000-51189 proposes a movable imaging system in which an X-ray control unit and a storage unit storing an X-ray film cassette are connected detachably.
Japanese Patent Laid-Open No. 2004-208716 proposes a digital X-ray imaging apparatus that does not use an X-ray film. For example, CR (Computed Radiography) using a photostimulable phosphor plate as an X-ray detector, and DR (Digital Radiography) in which a taken image is instantaneously displayed on a monitor are used. A movable imaging system in which these methods are applied to a mobile X-ray imaging apparatus has been proposed. An X-ray generation unit and a base unit are provided in a detachable manner. The base unit includes a power supply for the X-ray generation unit, and a high-voltage generator for applying a voltage to an X-ray tube in the X-ray generation unit.
Thus, a digital examination car in which a thin, lightweight, and portable FPD (Flat Panel Detector) is mounted can immediately perform image recognition and perform an image taking operation again, and development and cassette replacement during another image taking operation and multidirectional image taking operation are unnecessary. It is therefore possible to reduce the burden on a subject and an inspector and to achieve a high investigation accuracy.
In the movable X-ray imaging apparatus disclosed in Japanese Patent Laid-Open No. 2004-208716, however, an X-ray tube is held via a support and an arm having rigidity and provided in the main body of the apparatus, and the position and angle of the X-ray tube are changed by the support and the arm. The support and the arm increase the weight of the apparatus.
Further, the X-ray tube and the support protrude from the apparatus. To balance the apparatus against the protrusion, the apparatus needs to have a certain base area. Moreover, at least three wheels are necessary for stability. In addition, while the apparatus has a self running function to improve operability in response to the increase in weight, the self running function needs a power supply and a motor. This further increases the weight of the apparatus.
Consequently, size and weight reduction of the apparatus is difficult. In particular, it is difficult to use the apparatus in a site where portability is needed, for example, in a disaster area or at home for medical care. Further, there is much irregular ground in the disaster area, and high operability is required so as to quickly and precisely align the apparatus in accordance with various image taking conditions for the site.
Assuming that the X-ray imaging apparatus is used in an environment where a facility, such as an X-ray protective barrier, for preventing exposure to X-rays is not provided, it is preferable that the apparatus have less danger of exposure of parts of a subject other than a target part to be exposed, an X-ray photographer, and other persons.